My experience with the sight blade chart is that while for the most part it is accurate, there are some revolvers that for some reason have different height blades on them than as listed.
Now some of the revolvers I am finding variances on were not purchased new by me, so I can't swear that the blade had not been changed - but doubt it, however they do shoot perfectly and no extreme adjustments (up or down) were necessary.
I have ordered sight blades from the chart above and when said blade was installed, there have been an instance or two that I needed the next size up or down. Now whenever I need to order a new sight blade, I order the "chart spec" size and one up and one down. This has led to having some in stock if and when I need one for myself or a friend. It also lets me avoid additional freight charges for a simple part and I do have what I need in stock to get the repair done quickly. Just a suggestion......
Note:
There have been an ocassional time or two I have damaged a sight blade while competing and sometimes I just wanted to upgrade to a W/O rear sight or visa versa.
Smith and Wesson Customer Service should be able to confirm what the proper replacement blade height would be for your revolver. They will need the barrel length, model number and the serial number. 800-331-0852